Voltage doubler circuits



March 8, 1949. w. G. BIRD VOLTAGE DOUBLER CIRCUITS 2 Sheets-Sheet} 1 Filed Feb. 18, 1946 Time C Time INVENTOR.

William G. Bird Voltage E His Attorney March 8, 1949. w. RD 2,463;509

VOLTAGE DOUBLER C IRGU-I T S Filed Feb. 18, 1946 2 Sheets-Sheet 2 w Meun Value I 2v I i I I I I I I I I I I I I I I I V I I I I I I l I I I I I l I I l I l I A B C D A B C Time D INVENTOR.

William G. Bird His Attorney Patented 19 49 7 VOLTAGE DOUBLEB CIRCUITS William George Bird, Bristol, England, assignor, by mesne assignments, to Submarine Signal Company, Boston, Mass., a corporation of Delaware . Application February 18, 1946, Serial No. 648,491

This invention relates to voltage doubler circuits of the type using a double vibrator. A wellknown type of double vibrator makes use of two reeds mechanically coupled together by an armature bar of an electro-magnet which is energized periodically from the mains by reason of the provision with one of the reeds of a relatively displaceable contact which by reason of the influence of the electro-magnet on said bar is displaced to break electrical contact with'a lead forming part of the circuit in the electric-magnet, resulting in the armature reestablishing the contact to produce another impulse to maintain the armature and its associated reeds in vibration at a frequency depending upon the stiffness of the reeds and the relation of their masses to that of the armature.

It is well known that such a double vibrator can be utilized to develop from a direct current source of voltage of known value a voltage approximately equal to twice that value without the necessity of usin transformers, large rectifiers or their equivalent. However, this result does not always obtain. For example; when the appropriate load is effectively common with one side of the mains, e. g. when it is desired to apply voltages to the anode of a directly heated valve, the filament of which is ultimately connected to direct current mains either directly or through resistance, the voltage across the load becomes a very widely fluctuating one, in spite of the use of a conventional smoothing choke and a bypass condenser. The object of the present invention is to overcome this disability, this desideratum being achieved by employing in a suitable part of the circuit a rectifier in place of th aforesaid choke or resistance.

The invention will be more clearly understood by reference to the accompanying drawings in which Figure 1 shows a circuit appropriate to a known type of double vibrator;

3 Claims. (01. 320-1) appearing across the load with the circuit proposed in Figure 3;

Figure 4 is a diagram showing one embodiment of the present invention; and

Figure 4a is a diagram of the voltage cycle appropriate to the circuit shown in Figure 4.

Referring to the drawings in Figure 1 is shown diagrammatically the circuit appropriate to a double" vibrator of known type, in which the vibrator comprises two reeds I and 2, mechanically coupled together by a rigid bar '3 so as to vibrate in synchronism. Pairs of contacts 4, 5 and 6, I cooperate with the two reeds l and 2 respectively, and their positioning is such that The system is maintained in vibration by maliing the connecting bar 3 of soft iron and placing it adjacent to an electro-magnet 8, which is energized periodically from the mains through a contact HI cooperating with a split portion 9 of the reed 2. Thus if a voltage if from the mains Figure 1a shows the voltage changes which occur with the circuits shown in Figure 1;

Figure 2 shows a circuit in which one side of the load is effectively common with one side of be applied to the two reeds in the manner shown, there will, on switching on, be a magnetic incpulse tending to pull the bar 3 to one side. so breaking electrical contact between 9 and it. Thereupon the armature flies back until contact is remade and another impulse given, so main= taining the armature and its associated reeds in vibration at a frequency depending upon the stiffness of the reeds and their masses with that of the armature.

It is well-known that such a double vibrator can be utilized to develop from a direct current source of voltage V, a direct current voltage approximately equal to 2V without the necessity of using transformers, large rectlflers, or their equivalent. This is done in the circuit depicted in Figure 1, where H represents a suitable condenser across contacts 4 and 5, and I2 a similar condenser across contacts 6 and 1. The load to which it is desired to apply this double voltage is represented by l3. With this circuit it is apparent that the condensers l l and I2 are alternately coupled directly to the mains supply V and therefore very quickly charge up each to a voltage V, so that the total voltage E across the two would, in the absence of any load, be equal to 2V.

However, when there is. a load present, the voltage E changes in an obvious manner somewhat as depicted in Figure 1a, if the beginning nuances of the cycle A be taken to coincide with the time at which the reeds have just touched contacts l and '16 respectively. In this diagram the periods 38C and DA correspond to those periods when the reeds are touching neither contact and are roughly in the middle of their swing, so that the leakage from the condensers ii and i2 is somewhat increased during these periods, as shown.

it follows that the mean value of E actually appearing across the load will be somewhat less than 2V by an amount depending upon the sizes or the condensers ii and H2 in comparison with the load 63, and also that there will he a slight ripple on iii; this latter, however, can be eliminated if desired in the usual way by employing suitable chokes or resistances and by -passing condensers.

it more serious trouble arises, however, when one side of the load i8 is effectively common with one side of the mains, as depicted in Figure 2.

Such a case arises, for example, when it is desired to apply the voltage E to the anode of a directly heated valve, the filament of which is ultimately connected to the direct current mains even ii? through resistances. In this case it is easy to see, by following out a cycle of events, that the voltages E appearing across the load are as represented in Figure 2a. when the reeds l and ii are touching contacts 3 and respectively, the momentary voltage E is obviously the same as that across condenser M, which is V. Again, when the reeds are touching neither contact during phases BC and DA, the momentary voltage E is zero, since although the condensers ii and 02 remain substantially fully charged, there is now no closed circuit. On the other hand, when the reeds i and 2 touch contacts and l respectively, the voltage E will mo inentarily rise to a value 2V, because of the voltf remaining on condenser ll which is supernposed upon the voltage V across condenser l2.

ring this phase CD, however, the voltage I; will gradually fall as condenser ll discharges.

will thus be seen that the voltage E appearing across the load it is now a very widely fluctuone, and even though a conventional smoothing choke i l and by-pass condenser is be employed, as depicted in Figure 3, one can only hope to obtain ultimately a final mean value of (as depicted in Figure 3a) which is as much as above f, depending upon the relative lengths of the non-touching periods BC and DA in comparison with the touching periods All? and CD.

in order to overcome this disability, the circuit depicted in Figure 4 may be employed, in which circuit a rectifier it, with or without series resistance ill, is used in place of the croke or resistance l6 depicted in Figure 3. In this new circuit it is apparent that in the steady state both condensers ii and 62 are each charged up to a voltage of approximately V, and when the reeds l and 2 are touching contacts 5 and l, contact 6 will be at a potential approximately 2V relative to the negative side of the mains. Thus as long as the condenser i5 is at a potential less than 2V, current will tend to flow through the rectifier it during this phase of the cycle if the former be connected up in the right sense as shown. The charge thereby accumulated on condenser 85 cannot, however, flow back during the remainder of the cycle (when, for example, the reed l touches contact l) on account of the blocking action of the rectifier. It follows that the voltage across condenser it will tend to rise ii very quickly to a value nearly av and remain near this value to an extent depending upon the value of the condenser lll in relation to the load it. The voltage cycle is thus somewhat as depicted in Figure do.

It is clear that in the ultimate steady condition, the maximum reverse voltage to which the rectifier it will be sublect'ed occurs when reeds l and i? touch contacts 3 and 3, and is then equal to V. The maximum forward voltage to which it can be subjected is, however, 2V at the start when both condensers ii and 92 are charged but condenser is is uncharged. To prevent an excessive transient current passing at this moment, therefore, it may be advisable to insert in series with the rectifier a resistance As, moreover, current obviously only flows through the restitiier during the phase til) (i. c. with contact t at a potential 2V relative to the negative side of the mains), it is easy to calculate the average current through the rectifier if the value of the condenser 05 and load 03 be known. Hence, all the particulars can be ascertained for choosing a suitable unit.

Having now described my invention, 1 claim:

1. A voltage doubler circuit having a pair of series connected condensers arranged to be charged alternately from direct current source in such manner that the charges therein produce additive voltages in the circuit, wherein the load lines are connected one effectively to one side of the direct current source and the other to a point in the circuit which periodically expert ences a potential difference with respect to the first mentionedload line according to the sum of said additive voltages, the two load lines being shunted by a condenser, and a rectifier being included in said other load line between its point of connection with the circuit and the shunt condenser connection, such rectifier operating in a sense to prevent current from flowing bash from the shunt condenser towards the direct current source and the pair of series connected condensers.

2. A voltage doubler circuit having a pair of series connected condensers arranged to he charged alternately from direct current source in such manner that the charges therein produce additive voltages in the circuit, wherein the load lines are connected one effectively to one side of the direct current source and the other to a point in the circuit which periodically experiences a potential difference with respect to the first mentioned load line according to the sum of said additive voltages, the two load lines being shunted by a condenser, and a rectifier being included in said other load line between its point of connection with the circuit and the shunt condenser connection, such rectifier operating in a sense to prevent current from flowing back from the shunt condenser towards the direct current source and the pair of series connected condensers, a double vibrator being employed for charging the series connected condensers, said vibrator having two reeds joined one to each side of said source and four co-operating contacts of which a pair are joined in common to a tap between said series connected condensers and the other two contacts are joined to either side of said pair of condensers.

3. A voltage doubler circuit havinga pair of series connected condensers arranged to be charged alternately from a direct current source in such manner that the charges therein produce additive voltages in the circuit, wherein the load lines are connected one ell'ectively to one side of the direct current source and the other to a. point in the circuit which periodically experiences a potential difference with respect to the first mentioned load line according to the sum of said additive voltages, the two load lines being shunted by a. condenser, and a. rectifier being included in said other load line between its point of connection with the circuit and the shunt condenser connection, such rectifier operating in a sense to prevent current from flowing back from theshunt condenser towards the direct current source end the pair of series connected condensers and a resistor in one of said load lines to REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 2,255,299 Rockwell Sept. 9, 1941 2,267,233 Elstrom Dec. 23, 1941 

